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I understand the benefit of using maximum aperture, but that
also means that the exposures must be shorter before reaching skyfog. With
ISO 800 film with p = 0.71 at f/1.8 and skyglow of mag. 20 per square arcsecond
(roughly the amount of skyglow at our site), ASTREXP estimates an 11-minute
exposure for reaching skyfog. At f/2.8, it's 40 minutes, and at f/4 it's
1.8 hrs. Thus, going one stop from 1.8 to 2.8 allows the exposure to be
almost four times as long, and going to f/4 almost ten times as long, so I'm
wondering if I can make up for the reduced aperture and reduced ability to
record faint meteors by exposing for a much longer time before reaching
skyfog. I would not have the faint meteors, but I'd get more bright ones
because of the longer exposure.
-- Alson Wong Riverside Astronomical Society http://www.rivastro.org/ Visit my Web page at: http://home.earthlink.net/~alsonwong/index.htm ----- Original Message -----
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